The present invention relates to a solar electric power apparatus that is placed on a roof of a house, the top of a building or a wall, etc. and also concerns a solar module used therein and an installation method of solar modules.
The solar power-generation for converting light energy into electric energy by utilizing a photoelectric conversion characteristic been widely carried on as a means to obtain clean energy. Moreover, is the photoelectric conversion efficiency of a solar cell has been improved, solar electric power apparatuses have come to be installed in many private houses.
FIG. 1 is a cross-sectional view that shows a state in which a plurality of solar modules are placed on a roof of a private house so as to constitute such a solar electric power apparatus. In FIG. 1, reference number 1 represents a solar module, and each solar module 1 has a plurality of solar cells that have, photoelectric conversion function aid that are connected in series with each other.
These plurality of solar modules 1 are ranged on a roof 100 in a stepped manner from the ridge side to the eaves side with the edges of the adjacent solar modules 1 overlapped on each other. Such a stepped formation of the solar modules 1 refers to a stepped single-lap roofing.
In the case when a plurality of solar modules 1 are placed in a stepped manner, depending on the orientation of the installation, especially in the morning or evening when the sunlight has a low altitude, when the sunlight (arrow in FIG. 1) is directed from the ridge side, the solar module 1 placed on the upper side (ridge side) forms a shadow (hatched portion in FIG. 1) on the upper side of the solar module 1 placed on the lower side (eaves side), As a result, in the solar module 1 on the lower side (eaves side), the area covered with the shadow S does not allow the solar cell to generate power, thereby forming a great resistance and causing a reduction in the output. Moreover, since the solar cell forms a great resistance, heat is generated, and as the temperature rises, drawbacks such as gas generation from the back surface material, degradation in the solar cell or separation of the film, occur, resulting in a reduction in the output.
With respect to materials constituting a solar cell, a crystalline semiconductor such as single crystal silicon or polycrystal silicon, an amorphous semiconductor such as amorphous silicon or amorphous silicon germanium, or a compound semiconductor such as GaAs or CdTe is used. Among these, the solar cell using the amorphous semiconductor has a high degree of freedom in selecting the substrate and in designing the output system and is inexpensive in manufacturing costs; therefore, much attention has been focused on such a solar cell. However, in an arrangement in which a solar battery of an integrated construction having a plurality of sole; cell, being connected in series with each other on one common substrate is applied to the solar electric power apparatus, sufficient researches have not been made on the adverse effects of a shadow formed by the solar module placed on the upper side (ridge side) given to the characteristics of the solar electric power apparatus.
In a solar electric power apparatus which a plurality of solar modules are ranged, an object of in present invention is to provide a solar electric power apparatus that exerts superior output characteristics in particular, when a solar battery of an integrated construction is used.
Another object of the present invention is to provide a solar module that is free from adverse effects of a shadow formed by the solar module placed on the upper side when a plurality of solar modules are ranged and consequently makes it possible to prevent a reduction in the output, and also to provide an installation method for these solar modules.
In the solar electric power apparatus in the present invention provided with a plurality of solar modules that are ranged in such a manner that edges of adjacent solar modules are overlapped, each solar module is provided with a plurality of solar cells that are electrically connected in series with each other, and the serial connecting direction of the solar cells is set to a direction orthogonal to the ranging direction of the solar modules.
In the case when a plurality of solar modules are ranged in a stepped manner, for example, the solar module located on the lower side is subject to adverse effects given by a shadow of the solar module located on the upper side. In the case of the application of a solar battery of the integrated construction, when the solar modules are ranged with the serial connecting direction of the solar cells being coincident with a direction parallel to the ranging direction (eave-ridge direction), those solar cells covered with a shadow and those solar cells not covered with a shadow are located in a mixed manner in the solar module on the lower side, with the result that a reverse bias voltage is applied to those solar cells covered with the shadow and having a reduced output causing a possibility of cell damage. In contrast, in the present invention, since the solar modules are ranged with the serial connecting direction of the solar cells being set to a direction (a lateral direction) orthogonal to the ranging direction, each of the solar cells of the solar module located on the lower side is covered with a shadow in the same degree to that no problems are raised even upon generation of a shadow, thereby providing superior output characteristics.
Moreover, in the solar module of the present invention, an area in which no power is generated (non-power generation area) is installed in one side portion thereof, and these solar-modules are ranged in a stepped manner with the non-power generation area being located on the upper side (ridge side). In this installation state of the solar modules, when sunlight is directed from the ridge side, the shadow of the solar module on the upper side is formed on the non-power generation area of the solar module on the lower side; therefore, even when the solar modules are ranged with the serial connecting direction of the solar cells being coincident with a direction parallel to the ranging direction (eave-ridge direction), the portion in question does not form a great resistance, which makes it different from the conventional arrangement; thus, it is possible to prevent a reduction in the output of the solar modules, and consequently to obtain a stable photoelectric power.
When such a non-power generation area is installed, the amount of power generation tends to decrease. Therefore, it is preferable to correctly place the non-power generation area only at a portion covered with a shadow. In this invention, the length of the non-power generation area is set to not less than 10 mm and not more than six times the thickness of the solar module, or set to not less than 10 mm and not more than three times the thickness of the solar module in the case when the thickness of the solar module is not less than 20 mm. With this arrangement, it is possible to completely prevent adverse effects given by a shadow without causing a reduction in the amount of annual power generation. Moreover, this non-power generation area is easily formed by removing the solar cells at the corresponding portion.
Additionally, upon ringing a plurality of solar modules in a stepped manner, an interposition object made from a material that causes no adverse effects on solar electric power generation may be interpolated between the adjacent solar modules; thus, it is also possible to prevent adverse effects given by a shadow of the solar module on the upper side. In this case, the length of the interposition object is set in the same manner is the above-mentioned non-power generation area.
The above and further objects and features of the invention will more fully be apparent from the following detailed description with accompanying drawings.